JAKARTA, March 7 (Thomson Reuters Foundation) - Palm oil giant Wilmar on Tuesday denied accusations by a rights group that it had intimidated workers in an attempt to cover up a string of labour abuses from child labour to low wages on its Indonesian plantations.

Amnesty International in an investigation last November had found children as young as eight worked in "hazardous" conditions at palm plantations run by the Singapore-based firm and its suppliers in Indonesia.

Based on interviews with 120 workers, the rights group also claimed many of the workers worked long hours for low pay and without adequate safety equipment.

Amnesty said in a statement on Tuesday that Wilmar - the world's largest palm oil processor - had asked its workers to sign a document to deny the investigation findings during a recent meeting with trade union representatives.

Wilmar rejected the claim and said the union representatives had "voluntarily" signed the letters as "a show of support" to the company.

"Wilmar rejects the allegations of the company attempting to cover up abuse claims and intimidating staff," Perpetua George, the company's general manager of group sustainability said in an emailed statement to the Thomson Reuters Foundation.

Amnesty's investigation has found global consumer firms including Unilever, Nestle, Kellogg and Procter & Gamble, have sourced palm oil from Wilmar's plantations which are linked to the reported labour abuses.

The consumer firms have pledged to work with Wilmar to remedy any rights violations in their supply chain.

Amnesty urged Indonesia to investigate the matter.

"Workers on plantations live in fear of reprisals for speaking out about their poor working conditions," said Seema Joshi, Amnesty's head of business and human rights.

"Such reprisals could include being moved away from their families to a different plantation, or even losing their job entirely."

Indonesia's Manpower Ministry has said it has been trying to reduce child labour and it would improve labour protection at palm plantations. The ministry officials did not immediately reply to requests for fresh comment on Tuesday.